Motorcycles typically have a chassis, engine, and front and rear wheels. Motorcycles also typically include axles that couple the front and rear wheels to the chassis. Many motorcycles include mufflers that exhaust fumes from the engine toward the rear of the motorcycle.
Depending on the routing of the muffler, it may block access to the axle for the rear wheel. If the access to the axle is blocked, the muffler may need to be removed before the rear wheel can be removed. Having to remove the muffler before removing the rear wheel adds time and inconvenience to removing the rear wheel to change the rear tire, for example.